The development of a vertebrate body requires correct temporal and spatial activation of regulatory pattern forming genes. This laboratory is investigating the role of two families of pattern forming genes: the homeobox and forkhead genes. Special attention is devoted to those genes which are activated at the beginning of these pattern forming events. It has been found the expression of these genes is strongly altered by growth factors such as activin, TGF-beta, FGF and bone morphogenetic proteins. The results of these studies provides us with insights about the requirements for normal and abnormal development. Growth factors and bone morphogenetic proteins can directly influence the expression of pattern forming genes, i.e., genes responsible for the correct shape of the human body. A number of such products are in investigational use. The very same genes and products are being used in this laboratory to create rudimentary organs from undifferentiated ectodermal tissue, raising the possibility of future transplantation of organs and tissues grown in vitro.